TY - JOUR
T1 - A y+ LAT-1 mutant protein interferes with y+ LAT-2 activity
T2 - Implications for the molecular pathogenesis of lysinuric protein intolerance
AU - Sperandeo, Maria P.
AU - Paladino, Simona
AU - Maiuri, Luigi
AU - Maroupulos, George D.
AU - Zurzolo, Chiara
AU - Taglialatela, Maurizio
AU - Andria, Generoso
AU - Sebastio, Gianfranco
N1 - Funding Information:
This study was supported by grants from: Telethon Foundation-Italy (n.TCP99029) and San Paolo IMI to MP Sperandeo and MURST, Rome, COFIN 2002 and EUGINDAT EC FPVI (EC ref: LSHM-CT-2003-502852) to G Sebastio. MP Sperandeo is an assistant Telethon scientist (Dulbecco Telethon Institute (DTI), Telethon Foundation, Rome). We thank A Pepe for technical assistance.
PY - 2005/5
Y1 - 2005/5
N2 - Lysinuric protein intolerance (LPI) is an inherited aminoaciduria caused by defective cationic amino acid (CAA) transport at the basolateral membrane of epithelial cells in the intestine and kidney. The SLC7A7 gene, mutated in LPI, encodes the y+LAT-1 protein, which is the light subunit of the heterodimeric CAA transporter in which 4F2hc is the heavy chain subunit. Co-expression of 4F2hc and y+LAT-1 induces the y+L activity. This activity is also exerted by another complex composed of 4F2hc and y+LAT-2, the latter encoded by the SLC7A6 gene and more ubiquitously expressed than SLC7A7. On the basis of both the pattern of expression and the transport activity, y+LAT-2 might compensate for CAA transport when y+LAT-1 is defective. By expression in Xenopus laevis oocytes and mammalian cells, we functionally analysed two SLC7A7 mutants, E36del and F152L, respectively, the former displaying a partial dominant-negative effect. The results of the present study provide further insight into the molecular pathogenesis of LPI: a putative multiheteromeric structure of both [4F2hc/y+LAT-1] and [4F2hc/y+LAT-2], and the interference between y+LAT-1 and y+LAT-2 proteins. This interference can explain why the compensatory mechanism, that is, an increased expression of SLC7A6 as seen in lymphoblasts from LPI patients, may not be sufficient to restore the y+L system activity.
AB - Lysinuric protein intolerance (LPI) is an inherited aminoaciduria caused by defective cationic amino acid (CAA) transport at the basolateral membrane of epithelial cells in the intestine and kidney. The SLC7A7 gene, mutated in LPI, encodes the y+LAT-1 protein, which is the light subunit of the heterodimeric CAA transporter in which 4F2hc is the heavy chain subunit. Co-expression of 4F2hc and y+LAT-1 induces the y+L activity. This activity is also exerted by another complex composed of 4F2hc and y+LAT-2, the latter encoded by the SLC7A6 gene and more ubiquitously expressed than SLC7A7. On the basis of both the pattern of expression and the transport activity, y+LAT-2 might compensate for CAA transport when y+LAT-1 is defective. By expression in Xenopus laevis oocytes and mammalian cells, we functionally analysed two SLC7A7 mutants, E36del and F152L, respectively, the former displaying a partial dominant-negative effect. The results of the present study provide further insight into the molecular pathogenesis of LPI: a putative multiheteromeric structure of both [4F2hc/y+LAT-1] and [4F2hc/y+LAT-2], and the interference between y+LAT-1 and y+LAT-2 proteins. This interference can explain why the compensatory mechanism, that is, an increased expression of SLC7A6 as seen in lymphoblasts from LPI patients, may not be sufficient to restore the y+L system activity.
KW - Amino acid transport
KW - Lysinuric protein intolerance
KW - Mutation
KW - Xenopus laevis oocytes
KW - y LAT-1
KW - y LAT-2
UR - http://www.scopus.com/inward/record.url?scp=18844382599&partnerID=8YFLogxK
U2 - 10.1038/sj.ejhg.5201376
DO - 10.1038/sj.ejhg.5201376
M3 - Article
SN - 1018-4813
VL - 13
SP - 628
EP - 634
JO - European Journal of Human Genetics
JF - European Journal of Human Genetics
IS - 5
ER -